Many of the traditional definitions stress the relationship of food processing to the preservation of food, and this dimension still represents the single most important reason for processing.
These processes may be relatively simple such as the milling of wheat to produce flour or highly complex such as creating a pizza that to be cooked in a toaster.
Some of the earliest forms food processing resulted in dry food products. These references to various types of commodities date to very early times and the use of thermal energy from the sun to evaporate water from the product and establish a stable and safe dry product. Developing new complex today involves a lot of research experimentation, testing, and trialing.
A small scale recipe for a chicken korma cannot simply be multiplied up and used on a production line to create tens of thousands of meals.
Large scale machinery may affect food in a different way to a domestic cooker, causing meat to become tough or a sauce to runny. In general, processing is used to improve one or more properties of the food, with the underlying reasons falling into one (or more) of four categories: safety, quality value and convenience.
Although foods are always liquid or solid in form, many foods are aerated (e.g. ice cream), many processes utilize gases or vapors and many storage produces require gases or a particular composition.
Introduction to food processing